Fluid pump



W. W. PAGET Nov. 24, 1953 FLUID PUMP 5 Sheets-Sheet 1 Filed June 5, 1951 W/A/MPAGEZ 1Qw ATTORNEX W. W. PAGET Nov. 24, 1953 FLUID PUMP 5 Sheets-Sheet 2 Filed June 5, 1951 IIVI/EIVTOF' W/IV W. R4 gb? RZQM Arrow 5x W. W. PAGET Nov. 24, 1953 FLUID PUMP Filed June 5, 1951 5 Sheets-Sheet 5 lA/I/E N 7 0H W/IV M PAGET- 2 .2 rm

ATTORA/[K W. W. PAGET Nov. 24, 1953 FLUID PUMP 5 Sheets-Sheet 4 Filed June 5, 1951 Patented Nov. 24, 1953 FLUID PUMP Win W. Paget, Mountain Brook, Ala., assignor to Joy Manufacturing Company, Pittsburgh, Pa., a corporation of Pennsylvania Application June 5, 1951, Serial No. 230,041

11 Claims.

This invention relates to a fluid pump, especially to a fluid pump having a minimum rubbing velocity and a minimum of unbalanced centrifugal forces.

In spite of the very high stage of technological development reached by conventional reciprocating fluid pumps, they have disadvantages which are inherent in the design. It therefore becomes desirable to explore the possibilities of basically diiierent designs which have thus far not been so thoroughly exploited as the conventional reciprocating type of fluid pump and which do not have the limitations inherent in the more conventional types of design.

It is accordingly an object of this invention to provide a fluid pump having a minimum of rubbing contacts, a minimum rubbing velocity of moving contact surfaces, a maximum compression ratio for a given length of stroke, and high volumetric efliciency. This and other objects are accomplished in a flui-d pump, more specifically a compressor, comprising a housing having a piston element therein movable in such a manner that every point on the piston element describes a circle about a given point fixed with respect to the housing, and provided with suitable valves.

Still more specifically, the embodiment of the invention shown comprises a polygonal housing, preferably square, having a plurality of pumping or compression chambers equal in number to the number of sides of the polygon, a sealing surfaceproviding element at each corner of the polygon,

a piston element in the housing the same shape as but smaller than the housing, sealing elements slidably mounted in the corners of the piston element, means to move the piston element in the manner aforesaid, and suitable valves; for constant load conditions, the preferred valves are mechanical valves-4. e., valves which are positively opened and closed-and more specifically, plate type valves having elongated ports parallel with the sides of the polygon.

In the drawings:

Fig. 1 is a longitudinal sectional view through a machine made according to the invention; more specifically, Fig. 1 is a view in section substantially along the line ll of Fig. 2.

Fig. 2 is a view in section substantially on line 2-2 of Fig. 1.

Fig. 3 is a view in section substantially on line 3-3 of Fig. 1.

Fig. a is a view in section substantially on line of 4-4 of Fig. 1.

iii

Fig. 5 is a schematic diagram showing the relationship of the various centers of the rotating and otherwise moving parts to each other; and

Fig. 6 is a View in section similar to Fig. 1, but showing only a portion of the machine and illustrating another embodiment.

As will be well understood by those skilled in the art, a compressor made according to this invention may be driven by any suitable means as for example by an electric motor suitably geared to drive the compressor or an internal combustion engine of any suitable type. In the embodiment shown, an internal combustion engine flywheel 2 is shown as connected to drive the compressor shaft 4. Shaft 4 is mounted for rotation in any suitable bearings 6 and 8 which are carried by bearing support members l0 and 12 respectively. The bearing support [0 is carried by means of a suitable casing 14 and is connected thereto by threaded members I6, I! and I8. Casing I4 is secured to the crank case 20 of the internal combustion engine by means of threaded members one of which is shown at 22.

The threaded members It and I8 pass through the bearing support It and engage a compressor housing 24. In like manner, bearing support l2 and an end cover 26 are secured to the compressor housing 24 by means of threaded members 28 and 30. In addition, threaded members 32 are provided to secure an intermediate member 34 in place, the threaded members 32 passing through suitable openings in the intermediate member 34 and the bearing support member l2 and engaging threaded openings in the compressor housing 24.

A conduit is provided to conduct low pressure air from the low pressure discharge to an intercooler 38, this conduit comprising a duct 38, and portions of intermediate member 34 and a portion of the bearing support I2. Low pressure compressed air leaves the intercooler 36 by way of duct 48 and passes to the high pressure intake of the compressor, as will be understood by those skilled in the art. A fan 42 is suitably mounted on the shaft for rotation therewith and thereby to draw cooling air through the intercooler 36. Fan 42 is mounted for rotation in suitable bearings; more specifically, fan 42 is mounted on a sleeve 44 which surrounds the end of shaft 4 as shown in Fig. l, and which rotates in anti-friction bearing 46.

Shaft 4 is provided with an eccentric 48 between the bearings 6 and 8. Eccentric 48 provides the pumping motion for piston member 58.

Piston member 50 is provided with a sleeve 52, which in turn is provided with bearing sleeve inserts e4. Bearing sleeve inserts 54 in sleeve 52 are adapted to cooperate with bearing surfaces es provided at the ends or the eccentric 68.

As is best seen in Fig. 2, the interior of compressor housing 24 is polygonal in shape and is preferably a square having sides 24a, 24b, 24c, and 24d. Housing 24 is provided with an integral water jacket 62 providing spaces 54 for circulating cooling water. The compressor housing is provided with sealing surface-providing elements 66 at its corners or, more generally speaking, substantially at the intersection of the adjacent sides of the polygon forming the polygonal housing 24. More specifically, the housing 24, being polygonal in form, is provided at theporners with flattened portions 68, the flattened portions being recessed outward in ,order to provide grooves to receive the sealing surface-providing elements 66 The sealing surface providing elements 6% may be secured in the grooves in any of a number of conventional means well known to those skilled in the art, and need not be detailed here.

As is best seen in Fig. 2, the piston element 50 is of the same shape as the polygonal housing 24. In the embodiment shown, the housing 124 is square and the piston element 50 is also square, but smaller than the housing 2% in order to lit within that housing and to be movable inside the housing to provide the desired pumping action.

Sealing elements are provided in the comers of the polygonal piston element 50. As shown here, the sealing elements in the embodiment shown consist of vanes lil'which areradially slidable in slots (,2 provided in the corners of the piston element. As used here, the term radially,

des ri i g hem tion of th -sealing elements or vanes 'lll reiers to the fa;ct that the long axes of the van s 10 interse tion comm n point which is the e me ric center of the piston element '56, and the end closures (described'below) define four pumping or compression chambers, which may conveniently be designated 240A, 2403, 24CC, and 24GB.

It will of course be evident to those skilled in the art that the motion of diagonally opposite vanes with respect to the housing 24 is purely a sliding motion. In other words, the motion of a given pair of diagonally opposite vanes 18 with respect to housing 24 is such that the distance between the two vanes of said pair is a constant, or at least is constant to the extent that the associated elements 66 provide parallel surfaces. Means engaging the inner ends of the vanes or sealing elements '10 are provided to maintain a constant distance between the two vanes of a given pair. These means are in effect bridging members for the two vanes of a pair, or in other words are spacers, and assure that the two vanes of a pair move slidably (with respect to the piston member) in unison. Moreover, the means provided to space the two vanes of a pair, or to bridge the gap between grooves 73 in the ends of the bridging members is and 15. Inasmuch as the gap between the two vanes of a pair of diagonally opposite vanes is necessarybecause of the presence in that gap of the eccentric 18, the bridging members or spacers must be so designed as not to interfere with the movement of the eccentric cs. Accordingly, the loops l4 and T5 are elongated loops, and the eccentric 43 moves inside those loops without in any way interfering with the function or operation of the loops and without in any manner being hindered in its function by them.

jIt-will of course be evident to one skilled in the art that one bridging element H5 or 75 would theoretically suflice for its associated pair of diagonally opposed vanes i6, but in the preferred form of the invention shown in the drawings, two such bridging elements M are shown, and also two bridging elements '16 are shown. The two such elements are in each case spaced apart as far as possible along the longitudinal axis of the eccentric 48. See Fig. 1. This arrangement gives a maximum of stability to the operation and sealing engagement of the vanes 13.

Rotation of the eccentric t8 inside the bearings 54 of the piston element 58 will set up a torque which tends to rotate the piston element at about the axis of shaft d (point B in Fig. 2). To provide the desired pumping motion, the geometric center of the piston element 55 represented as A in Fig. 2, must revolve about the housing or shaft center B in much the same manner as a planet revolves around its sun, but successful operation of a fluid pump made according to this invention requires that the piston element 59 not rotate about its own center. Accordingly, means are provided to move the piston element in such a manner that every point on it describes a circle, the circles of movement of any two points being equal.

The aforesaid means includes of course the shaft 4, the eccentric it, and the bearing in the piston member 50 made up of the bearing sleeves 54; the means also includes a pair of idler shafts, one of which is shown at in Fig. l, rotatably mounted in a bearing 82 in the bearing support I0. Theoretically, one such idler shaft will suffice, but two are provided for greater stability. Each of idler shafts 8% is provided with an eccentric, one of which is shown at 83 in Fig. l, the eccentricity of the eccentric i l with respect to the idler shaft 80 being precisely the same as the eccentricity of the eccentric 58 with respect to the main shaft 4. Eccentric 84 is rotatable in the piston element 58 in a bearing 85.

Valve means are provided to permit inlet and discharge of a fluid with respect to the compressor housing. These valve means may be conventional check valves, sometimes known as automatic valves, and are here shown as springbiased inlet and discharge valves, disposed about the sides of the polygon of the polygonal housing in a manner which will be understood by those skilled in the art. As a matter of fact, in the embodiment shown in Fig. 5, the discharge valves are such conventional, spring-biased valvesias will be pointed out in greater detail below.

In the preferred embodiment of the invention shown in Figs. 1-5, mechanical valves are shown, for a compressor made according to this invention which will be used Where air (or other gas) is required at a constant or very nearly constant pressure. In this embodiment, the valves are septum-providing means forming the end closures referred to above. For applications in which the pressure varies, the adaptation shown in Fig. 6 or one similar thereto will be used. In the preferred embodiment of Figs. 1-5, the inlet valves are shown at the right end of housing 24 in Fig. 1 and comprise a plate having elongated ports therein-the long axes of the ports being parallel to the sides of the polygon forming the polygonal housing.

Thus the inlet valve means referred to is a platelike member 86 substantially circular in appearance as is readily seen in Fig. 3 with its inner face in contact with the face 87 of housing 24, and having elongated openings or ports, 88, 90, 92 and ea. As will be well understood by those skilled in the art, the elongated ports 88- 94 alternately move across the corresponding edges 2402 5d of the polygonal housing. As the ports move across those edges toward the interior of the housing, moving off the face 3?, they are opened and allow the gas which is being compressed to enter the housing. Thus it can be seen from Fig. 3 that the elongated port at is entirely over the face 8'! of the housing, and no gas can enter the compression chamberv MCD by way of port 9%. Port 83 on the other hand is completely open, because its extreme outer edge is substantially coincident with the inner edge 240.. Port is is approximately half open, as can be seen from the fact that the edge 24b of the housing substantially bisects the elongated port 98 along its long axis. Elongated port 92 is, like port 94, completely closed because it is outside the edge 240 of the housing.

Means are provided to move the septum 86 to furnish the necessary valve action. means comprise the shaft 4 and an eccentric 95 mounted on the shaft. Inasmuch as the eccentric 43 is the first mentioned eccentric on shaft 4, the eccentric 85 is of course another eccentric on the same shaft. Eccentric 96 engages a suitable circular bearing surface in the septum 85. Reference will now be made to the eccentricity of the eccentric Qt. It will be recalled that, in the above discussion of the eccentricity of eccentric 48, the letter B was used to designate the axis of shaft :3 (Fig. 2). Similarly, in Fig. 3 the letter B indicates the axis of shaft 4. The letter C in Fig. 3 indicates the axis of eccentric 95. The distance BC thereupon represents the eccentricity of eccentric 9t, and twice the distance BC therefore of course is the length of stroke of the valve septum 86.

As will be understood by those skilled in the art, there is a tendency on the part of the valve septum or disk 36 to rotate about the center B. In order to prevent such rotation and to insure the planetary type of motion that is necessary for the desired valve action, means are provided including an idler shaft and an eccentric thereon having a throw or eccentricity which is exactly equal to the eccentricity represented by the distance BC.

In the preferred form of the invention two such idler shafts are provided. Furthermore, the idler shaft thus required is conveniently the same These 1 6 as the idler shaft used to keep the piston member 50 from attempting to rotate about the shaft axis. More specifically, the two idler shafts are those shown at in Figs. 1 and 3 (the crosshatched portion appearing in Fig. 3 is a small connecting portion of the shaft which joins the eccentric and the bearing portion of the shaft).

An eccentric 98 is provided to engage the septum 86 and insures that the septum 86 will have the desired planetary motion. It will of course be understood that the eccentricity of eccentrics 93 is exactly equal to that of eccentric 95. Eccentric 98 engages suitable bearing surfaces provided in the septum 86.

In a similar manner, discharge valve means comprise a septum which is a platelike member I 00 in contact with face ID! of housing 24 and having elongated openings or ports I02, H14, H35 and H38. See especially Fig. 4. As seen in that figure, ports I62 and its are closed by face It! and thus are not in position to permit the discharge of fluid from the compressor housing. Port I05 on the other hand is about half uncovered, inasmuch as edge 24c substantially bisects the port H35 along its long axis. Port Hit is also outside the edge defining the interior of the housing, namely 24b, and accordingly is not in position to permit the discharge of any fluid from the housing.

Means are provided to move the septum its to furnish the necessary motion for the desired valve action. These means comprise an eccentric illl secured to shaft 4. In order to permit easy assembly of the compressor, the eccentric H6 is preferably not integral with shaft 4 but is a separate member secured to shaft i in a suitable manner not detailed here. As in Figs. 2 and 3. the letter B in Fig. 4 also designates the axis of rotation of shaft 6 and the letter I) designates the center of eccentric Ht. Accordingly the ecccntricity is represented by the distance BD, and the length of stroke is of course twice the distance BD.

As was pointed out above, means are provided to keep the inlet valve plate from rotating about the axis of shaft A. Similarly, means provided to prevent the rotation of discharge valve plate its about the shaft axis, these means com prising a pair of idler shafts having eccentrics thereon engaging the valve plate. Thus idler shafts H2 are rotatably mounted in the bearing support it which is provided with suitable bear ings to receive the idler shafts HZ, one such bearing being shown at lid in Fig. l. (The portion of shaft H2 which appears cross-hatched in Fig. 4 is the connecting portion between the actual eccentric and the bearing portion.) Eccentrics I iii are provided on the idler shafts 5 if. the eccentricity of eccentrics HE; being necessarily equal to that of eccentric l l3.

Reference is now made to Fig. 5 which shows the relationship of the various and so centrics to each other. In order to avoid confusion, only one of the idler shafts for each of the valve plates is shown in Fig. 5. As there shown, the point B represents the axis of rotation of shaft 4 and therefore of course also the center of the bearings 5 and 5 in which shaft i rotates. The points B represent the axes ro tation of the idler shafts, and therefore of course are also the centers of the bearings in which the idler shafts rotate. The point marked A represents the center of the eccentric es and therefore also of course the center of the piston element. The point A represents the center of the eccentric B4. The point C represents the center of eccentric 96 and also incidentally the center of the inlet valve plate 86. The point C represents the center of eccentric 98. Similarly, the point D represents the center of eccentric H6, and the point D represents the center of eccentric H6.

It will be understood by those skilled in the art that lines AB and A'B' must be parallel or substantially so to get the desired motion. Similarly, lines BC and BC are parallel and lines BD and BD are parallel.

Reference is now made again to Figs. 1 and 2 for a discussion of the unloading means for a compressor made according to this invention. As will be understood by those skilled in the art, sweep control unloading is used, provided by unloader valves indicated generally by the refer-- ence characters H8, I26, I22 and i2-tone such valve for each compression or pumping chamber of the compressor. In the embodiment shown, the three compression chambers served by unloader valves I 18, I26 and !22, namely chambers 240D, 250A and H08 respectively, constitute low pressure compression chambers, and cham ber 2408, served by the valve 12d, constitutes a high pressure compression chamber.

The unloader valves are conventional springbiased valves, being the same as might be used as inlet valves. As a matter of fact, the valves H8|2 l could actually be used in a compressor of this design as inlet valves. In the embodiment shown, the valves occupy a space which is at inlet pressure, and the valves will open if the pressure in their associated compression cham bers drops far enough below the pressure in the inlet passages of the compressor before the mechanical inlet valves open. Thus, as is best seen in Fig. 1, inlet passage i26 of the compressor is in communication with the interior of the unloader valve H8 by way of a passage :28 in the compressor housing.

Inasmuch as the four unloader valves are substantially identical, it will sufiice to describe one of them in sufficient detail to assure a complete understanding of the invention. Thus the valve H3 is provided with valve disks L36, and i322 which engage suitable seats as will be understood by those skilled in the art, and which are biased into engagement with those seats by springs its and [3-6 respectively. A piston :38 is reciprocable in a cylinder M6, and is located immediately below a diaphragm M2. Control pressure is admitted to the upper side of diaphragm Hi2 through a passage Hit in a connection [56, and through a passage H38 in a cylinder head I56. The piston [36 is provided with a plurality of elongated fingers 252 which extend inward into engagement with the valve discs 13! and L32. Thus the application of control pressure to the upper surface of diaphragm hi2 forces piston 38 downward, whereupon the inner ends of fingers i52 engage the valve discs 136 and I32, serving to open those valve discs against the bias of their associated springs I34, and 36, holding the valves open and preventing the compression of the gas in the associated compression chamber.

Reference is now made to Fig. 6, wherein is shown another embodiment of the invention, this embodiment being one which is adapted to a variable load. The compressor there shown is the same as that shown in Figs. 1-5 except that the discharge valves are of the automatic type rather than the mechanical type shown in Figs.

1-5. Howeveneven in the embodiment shown in Fig. 6, the inlet valves are of the mechanical type, namely the plate type having the plurality of elongated openings discussed in detail above.

In the embodiment shown in Fig. 6, instead 01 a discharge plate valve such as is shown at I66 in Figs. 1 and 4, a fixed plate I54 is provided at the left end of the compressor housing. Instead of the plate type mechanical discharge valve, an automatic discharge valve is provided for each compression chamber of the compressor, the automatic valve being a conventional type such as the one shown at I56, in which valve discs I58 and I60 seat against suitable surfaces, and are held in engagement with their seats by springs I62 and I64 respectively. In view of the scale to which Fig. 6 must be drawn to show the overall organization, many fine line details of the valve cannot be brought out without making the drawing confusing. The automatic valve shown may be any of a number of suitable conventional valves, but is preferably like the valve shown in Fig. 4 of Patent 2,487,126 granted to Ferguson and assigned to the assignee of this application.

One of the advantages of a compressor made according to this invention is that it is easier to balance the centrifugal forces. There are numerous sources of centrifugal force in the compressor, these arising from the various eccentrics and from the planetary rotation or movement of the piston element 56. To balance the centrifugal forces set up by the sources indicated, counterweights I66 and I63 are secured to the left and right ends respectively of shaft 4. See Figs. 1 and 6.

Operation As shaft 4 rotates, the eccentrics 48 and 84 cause the piston element 50 to move in such a manner that every point on the piston element describes a circle about a given point fixed with respect to the compressor housing 24. Another concept of the motion of the piston element is that it is planetary with respect to the center B of the shaft 4. As the piston element 50 moves in the manner indicated, each side of the polygonal piston element approaches the associated side of the compressor housing and, having approached as closely as the eccentricity of the eccentric 48 permits, begins to recede. The various piston element sides approach their associated compressor housing sides in a given sequence, and of course recede from those sides in the same sequence.

As the piston element 50 moves through the path described above, it serves to slide the vanes or sealing elements 10 on the sealing surfaceproviding elements 66. Diagonally opposite vanes maintain a fixed distance and are spaced apart by their associated loops or spacers H3 or 16 as the case may be. However, with respect to the piston element 56, the vanes ill have a radial sliding motion in the corners of the piston element.

As shaft 4 rotates it drives the inlet valve plate 86 in a planetary manner by means of the eccentrics 96 and 98, valve plate 86 moves in the manner indicated, the ports 88, 90, 92 and 9d uncover in sequence to admit fluid from their associated inlet passages in the bearing support ill into the several compression chambers of the compressor, where the fluid is compressed.

Similarly, rotation of shaft 4 causes the discharge valve plate I00 to go through a planetary motion whereupon the ports I62, I94, I06 and I08 are uncovered in sequence to allow compressed fluid to discharge from the compressor to the discharge passages provided in the bearing support l2. Unloading of the compressor is accomplished by means of the unloader valves I I8, I20, I22 and I24 in a manner which will be understood by those skilled in the art from the foreoing description and which need not be repeated here.

The operation of the embodiment shown in Fig. 6 is similar to that of the embodiment shown in Figs. 1-5, except that in Fig. 6, discharge of fluid from the several compression chambers is by way of the automatic spring-biased check valves, one of which is shown at I56, instead of by way of ports provided in a mechanical valve.

It will be evident to those skilled in the art that this invention provides a compressor providing for easy balancing of the centrifugal forces, providing a compressor with small clearance volume, a small number of moving parts, low rubbing velocities, and high volumetric efiiciency. Other advantages will be apparent to those skilled in the art.

While there is in this invention specifically described two forms which the invention may assume in practice, it will be understood that these forms of the same are shown for purposes of illustration, and that the invention may be modified and embodied in various other forms without departing from its spirit or the scope of the appended claims.

I claim:

1. A fluid pump comprising a polygonal housing having a sealing surface at the intersection of each pair of adjacent sides of said housing, a piston element in the housing of the same shape as the housing, sealing elements slidably mounted in the corners of the piston element and having outer edges in sealing engagement with the ceiling surfaces, means to impart movement to the piston element such that every pcint thereof describes a circle, septum providing means enclosing the housing ends, and valve means permitting inlet and discharge of a fluid with respect to the housing, the housing, piston element, sealing elements, and septum providing means forming a plurality of pumping chambers, and at least one of the valve means comprising one of said septum providing means provided with elongated ports disposed with their long axes substantially parallel to the sides of the polygonal housing.

2. A pump as in claim 1, and means connected to impart motion to said one of the septum providing means such that each point thereof moves in a circle.

3. A pump as in claim 2, in which said septum motion imparting means includes a shaft provided with an eccentric, said eccentric engaging the septum providing means, and an idler shaft having a similar eccentric also in engagement with the septum providing means.

4. A fluid pump comprising a polygonal housing having a pumping chamber at each side thereof, the housing having a sealing surface at the intersection of each pair of adjacent sides there of, a piston element in the housing of the same shape as the housing, sealing elements slidably mounted in the corners of the piston element and having outer edges in sealing engagement with the sealing surfaces, the housing, piston element, and sealing elements forming boundaries of the pumping chambers, means to impart movement to the piston element such that every point thereof describes a circle, and valve means permitting inlet and discharge of a fluid with respect to the several pumping chambers, the movement-imparting means including a shaft provided with an eccentric, the eccentric engaging the piston element, and an idler shaft having a similar eccentric also in engagement with the piston element.

A fluid pump comprising a polygonal housing having a pumping chamber at each side thereof, the housing having a sealing surface :"cr each pair of adjacent sides, a piston element in the housing of the same shape as but smaller than the housing, sealing elements slidacly mounted in the corners of the piston elemerit and having outer edges in engagement with the sealing surfaces, means to impart movement to the piston element such that every point on it describes a circle, and valve means permitting inlet and discharge of a fluid with respect to the housing, the housing, piston element, sealing elements, and valve means defining the several pumping chambers.

6. A fluid pump comprising a polygonal hous ing having a pumping chamber at each side thereof, the housing having a sealing surface at the intersection of each pair of adjacent sides thereof, a piston element in the housing of the same shape as the housing, sealing element slidably mounted in the corners of the piston element and having outer edges in sealing engagement with the sealing surfaces, means to impart movement b0 the piston element such that every point thereof describes a circle,valve means permitting inlet and discharge of a fluid with respect to the housing, the housing, piston element, and sealing elements forming boundaries of the pumping chambers, and a plurality of unloading valves spaced about in the periphery of the housing, one unloading valve for each pumping chamber and connected to unload its associated chamber.

'7. A pump as in claim 6, in which the inlet and discharge valve means also form boundaries of the pumping chambers, and in which the unloading valves occupy space which is in communication with the inlet valve means.

8. A pump as in claim 7, in which the pump is a multi-stage pump comprising a plurality of low pressure stage pumping chambers and at least one high pressure stage pumping chamber.

9. A fluid pump comprising a housing having a plurality of pumping chambers spaced about its periphery, the housing having sealing surfaces spaced about the interior thereof, a piston element in the housing of the same shape as the housing, vanes equal in number to the sealing surfaces and mounted in opposed relation in the piston element in alinement with the sealing surfaces for sliding movement only with respect to said piston element and having outer ends in sliding engagement with the sealing surfaces, the housing, piston element, and sealing elements forming boundaries of the pumping chambers, means engaging the inner ends of the vanes to hold the vanes with their outer ends in engagement with the sealing surfaces as aforesaid and to assure movement in unison of opposed vanes, means to impart movement to the piston element such that every point on the piston element moves in a circle, the circles of movement of any two points on the piston being substantially equal, valve means permitting inlet and discharge of a fluid with respect to the pumping chambers, the inlet valve means comprising an element having a plurality of elongated ports, and means to move said inlet valve element so that every point -11 thereon describes a circle, said piston and ele ment moving means comprising a shaft having an eccentric connected to the piston and a second ecccentric in engagement with the inlet valve element.

10. A fluid pump comprising a housing having inlet and discharge ducts and having a plurality of pumping chambers spaced about its periphery, the housing having sealing surfaces spaced about the interior thereof, a piston element in the housing of the same shape as the housing, vanes equal in number to the sealing surfaces and mounted in opposed relation in the piston elee ment in alinement with the sealing surfaces for sliding movement only With respect to said piston element and having outer ends in sliding engagement with the sealing surfaces, the housing, piston element, and sealing elements forming boundaries of the pumping chambers, means engaging the inner ends of the vanes to hold the vanes with their outer ends in engagement with the sealing surfaces as aforesaid and to assure movement in unison of opposed vanes, means to impart movement to the piston element such that every point on the piston element moves in a circle, the circles of movement of any two points on the piston being substantially equal, valve means permitting fluid communication between the pumping chambers and said ducts, and a plurality of check valves other than said valve means spaced about in the periphery of the housing, at least one check valve for each 12 pumping chamber and in communication therewith, said valves being in communication also with one of said ducts, thereby permitting addie tional communication of the pumping chambers with one of said ducts.

11. A fluid pump comprising a housing having a plurality of pumping chambers spaced about its periphery, the housing having sealing'surfaces spaced about the interior thereof, a piston element in the housing, sealing elements mounted for sliding movement only in the periphe cry of the piston element and having outer edges in sealing engagement with the sealing surfaces, the housing, piston element, and sealing elements forming boundaries of the pump: ing chambers, means to impart movement to the piston element such that every po nt thereon describes a circle, and valve means permitting inlet and discharge of a fluid with respect to the pumping chambers.

WIN W. PAGET.

Refers-me cite n the f e f s pate UNITED STATES PATENTS 

